Answer:
1. Just at this point of my progress, Mr. Auld found out what was going on, and at once forbade Mrs. Auld to instruct me further, telling her, among other things, that it was unlawful, as well as unsafe, to teach a slave to read.
2. He would at once become unmanageable, and of no value to his master.
Explanation:
The two sentences above show that Mr. Auld did not think that education and slavery were compatible. On learning that Frederick Douglass was now learning how to read and write from his wife, he immediately stopped her, insisting that it was not safe to teach a slave how to read and write.
He reasoned that if Douglass became literate, he would become unmanageable. He might now challenge the authority of his master and become of no use to him.